China News Agency, Beijing, May 22 (Reporter Sun Zifa) May 22, 2020 is the 60th anniversary of the largest earthquake of magnitude 9.5 in Chile, the world's largest earthquake since instrumental records. According to the Public Service Department of the China Earthquake Administration, the earthquake hit the two largest in the world, with the largest magnitude, the largest impact range and the most severe earthquake tsunami. Researcher Han Libo of the Institute of Geophysics, China Earthquake Administration emphasized that as one of the scientific enlightenments, strengthening seismic fortification and preventing buildings from collapsing during earthquakes are the key to reducing casualties.
The release of energy is equivalent to 180 Wenchuan magnitude 8 earthquakes
The popular service department of the China Earthquake Administration said that the Chilean earthquake of magnitude 9.5 that occurred on May 22, 1960, hit the most in two worlds: one is the largest earthquake recorded by instruments in the history of seismic observation so far; The earthquake with the largest and most severe impact on the tsunami caused a huge disaster for mankind.
The magnitude of an earthquake is a classification of the amount of energy released by the source. Each time the magnitude differs by one level, the difference in energy released by an earthquake is about 31.6 times. The 9.5 magnitude earthquake in Chile is equivalent to the energy released by 180 Wenchuan magnitude 8 earthquakes.
In terms of triggering the tsunami, after the 9.5-magnitude earthquake in Chile that year, the seawater on the east coast of the Pacific suddenly receded, exposing the bottom of the sea. After about 15 minutes, waves up to 8 meters to 9 meters and up to 25 meters surged, hitting Chile and the Pacific In the cities and villages on the east coast, waves created by the earthquake swept across the Pacific Ocean at a speed of 700 kilometers per hour.
From May 21 to June 22, 1960, hundreds of earthquakes occurred continuously in Chile, including 3 over 8 and 10 over 7, and 9.5 is the largest main shock. During the earthquake, 6 extinct volcanoes renewed Three eruptions appeared.
The coastal areas of China are protected by peripheral islands and are less affected by the earthquake and tsunami. However, the tide gauge stations in the East China Sea and the South China Sea recorded the waves caused by the earthquake and tsunami that year.
The earthquake was caused by the subduction of the Nazca plate below the South American plate
"60 years have passed, and the scientific research and exploration around this huge earthquake have never stopped." Han Libo pointed out that the Pacific Rim Seismic Belt concentrated most of the world's earthquakes. The Chilean 9.5 magnitude earthquake occurred in the Pacific Rim Seismic Belt. West Coast area of South America.
The Pacific Rim seismic zone is mainly caused by the subduction of the Pacific plate towards many plates in the surrounding areas of the Pacific Rim. The so-called subduction is the movement process that occurs at the confluence of tectonic plates due to the movement of one plate below another plate. The area where this phenomenon occurs is also called the subduction zone. The subduction zone, due to its structure and movement mode, allows the accumulation of more stress concentration and release, so it will produce the strongest earthquake on the earth. Among the 10 strongest earthquakes in the 20th century, including the 9.5 magnitude earthquake in Chile, there are 9 It is this type of earthquake.
He said that the 1960 magnitude 9.5 earthquake in Chile was caused by the subduction of the Nazca plate below the South American plate. The Nazca plate is an oceanic tectonic plate located in the East Pacific Basin off the west coast of South America, and the South American plate is a large tectonic plate that includes the South American continent and the Atlantic seabed. The subduction of the trench caused the release of stress and triggered the largest earthquake to date.
Strengthening anti-seismic fortification is the key link to reduce casualties
Han Libo believes that although the Chilean 9.5 magnitude earthquake caused serious casualties and disaster losses, compared with its huge magnitude, the number of casualties was lower than expected. Although the buildings were severely damaged, only a handful of buildings collapsed. This is because many buildings in Chile are built in strict accordance with earthquake resistance standards and have contributed to the protection of personnel. It can be seen that strengthening seismic fortification and preventing buildings from collapsing during earthquakes are the key links to reduce casualties.
The earthquake expert also specially reminded that although a major earthquake is a rare event, it still requires the public to strictly implement the relevant laws and regulations. It must not be a fluke because the earthquake is a small probability event, nor can it be paralyzed by thinking that it is far away from the earthquake zone.
He said that before the 1960 earthquake of magnitude 9.5 in Chile, there were two pre-seismic activities of magnitude 7 and above. In addition, there was also a foreshock activity before the 2014 Iquique M8.1 earthquake in Chile. The correlation between the high-magnitude foreshock activity before these giant earthquakes and the subsequent major earthquakes still needs in-depth study.
In recent years, Chile has teamed up with Germany, France and other countries to establish the Chilean Plate Boundary Comprehensive Observation Station, which specializes in researching earthquakes and deformations on the continental margin of Chile, improves the understanding of seismic physical processes, and helps develop new generation risk assessment and prediction tools. "It can be expected that with the continuous improvement of modern observation networks and the deepening of research, people's scientific understanding of earthquake laws and the ability to prevent and control earthquake disaster risks will also be continuously improved and strengthened." Han Libo said. (Finish)